Genomic analysis of Brucella melitensis reveals new insights into phylogeny and evolutionary divergence.

PURPOSE: Brucellosis is a bacterial zoonotic disease caused by genus Brucella. The disease is often transmitted to humans by direct or indirect contact with infected livestock or from laboratory exposure. In this study two clinical isolates of Brucella melitensis were subjected to whole genome sequencing (WGS) using Ion Torrent PGM and Oxford Nanopore MinIon platform. METHODS: The two hybrid complete genomes were subjected to core gene SNP analysis to identify the relative evolutionary position. To distinguish between the various lineages of B. melitensis, Pangenome analysis was carried out. RESULTS: Phylogenetic analysis revealed that both the study isolates (ST8) clustered along the other Asian isolates that formed genotype II. Genome wide analyses of 326 B melitensis isolates suggests 2171 gene clusters were shared across all the genomes while 3552 gene clusters were considered as accessory genes. CONCLUSION: Here we attempted to provide the gain and loss of six unique genes that defined the phylogenetic lineages and complex evolutionary process. As the severity and prevalence of human brucellosis is increasing a better understanding of Brucella genomics and transmission dynamics is needed.

Vancomycin heteroresistance in Staphylococcus haemolyticus: elusive phenotype.

AIM: To determine the presence of vancomycin heteroresistance in Staphylococcus haemolyticus. MATERIALS & METHODS: A total of 48 rifampicin-resistant S. haemolyticus isolates from bloodstream infections were included. Vancomycin heteroresistance was determined using the population analysis profile-area under curve (PAP-AUC) method. All the isolates were screened for the presence of mecA gene, mutations in the rpoB gene, staphylococcal cassette chromosome mec and multilocus sequence types. RESULTS: Fifteen isolates were identified as heteroresistant vancomycin-intermediate S. haemolyticus using PAP-AUC method. Dual rpoB mutations (D471E and I527M) contributed for the rifampicin resistance. The sequence types of heteroresistant vancomycin-intermediate S. haemolyticus were highly diverse. CONCLUSION: These findings illustrate the potential of S. haemolyticus to develop heteroresistance, which emphasizes the need for routine surveillance of S. haemolyticus isolated from intensive care units for infection control practices.

Evaluation of Antimicrobial Susceptibility Profile in Salmonella Typhi and Salmonella Paratyphi A: Presenting the Current Scenario in India and Strategy for Future Management.

BACKGROUND: Systematic studies to estimate the disease burden of typhoid and paratyphoid in India are limited. Therefore, a multicenter study on the Surveillance of Enteric Fever in India was carried out to estimate the incidence, clinical presentation, and antimicrobial resistance (AMR) trend. The data presented here represent the national burden of AMR in Salmonella Typhi and Salmonella Paratyphi A. METHODS: Antimicrobial susceptibility testing was performed for S. Typhi and S. Paratyphi A (n = 2373) isolates collected prospectively during a 2-year period from November 2017 to January 2020. RESULTS: Of 2373 Salmonella isolates, 2032 (85.6%) were identified as S. Typhi and 341 (14.4%) were S. Paratyphi A. Approximately 2% of S. Typhi were multidrug-resistant (MDR), whereas all 341 (100%) of S. Paratyphi A isolates were sensitive to the first-line antimicrobials. Among 98% of ciprofloxacin nonsusceptible isolates, resistance (minimum inhibitory concentration [MIC] >0.5 µg/mL) was higher in S. Typhi (37%) compared with S. Paratyphi A (20%). Azithromycin susceptibility was 99.9% and 100% with a mean MIC of 4.98 µg/mL for S. Typhi and 7.39 µg/mL for S. Paratyphi A respectively. Ceftriaxone was the only agent that retained 100% susceptibility. Moreover, beta-lactam/beta-lactamase inhibitors showed potent in vitro activity against the study isolates. CONCLUSIONS: Data obtained from this systematic surveillance study confirms the declining trend of MDR Salmonella isolates from India. The higher prevalence of ciprofloxacin nonsusceptibility enforces to limit its use and adhere to the judicious usage of azithromycin and ceftriaxone for enteric fever management.

Draft genome sequence of carbapenem-resistant Elizabethkingia anophelis strain BP8467 clinical isolate from India.

OBJECTIVES: Elizabethkingia spp. are Gram-negative, glucose-non-fermenting bacilli that are ubiquitous in natural environments such as soil, plant and water sources. Besides environmental sources, the bacterium can be found in hospital environments, particularly medical equipment and reagents. Here we report the draft genome sequence of an Elizabethkingia anophelis isolate from a blood culture. METHODS: Genomic DNA of E. anophelis strain BP8467 was sequenced on an Ion Torrent PGM platform and the reads were assembled de novo using SPAdes v.5.0.0. The draft genome was annotated using the Prokaryotic Genome Annotation Pipeline (PGAP) v.4.9. Genetic determinants of antimicrobial resistance as well as virulence factors were identified using computational tools. RESULTS: The assembled draft genome is 3859105bp in length with a G+C content of 35.62% distributed in 30 contigs. Presence of the blaBlaB and blaGOB-4 genes associated with resistance to carbapenems was identified. In addition, genes conferring resistance to other ß-lactams (blaCME-1), aminoglycosides [ant(6)-I] and chloramphenicol (catB) were also detected. Antimicrobial susceptibility testing showed that the isolate was susceptible to levofloxacin, trimethoprim/sulfamethoxazole, tetracycline and rifampicin. CONCLUSION: The presence of a multidrug-resistant isolate harbouring diverse antimicrobial resistance genes along with numerous virulence factors suggests the risk associated with Elizabethkingia spp. infections. This genome analysis provides insights into the antimicrobial resistance and pathogenicity mechanisms of multidrug-resistant E. anophelis that can help in the management of Elizabethkingia spp. infections in the future.

Bad bug, no test: Tigecycline susceptibility testing challenges and way forward.

Tigecycline is a reserve antibiotic increasingly used for the treatment of multidrug-resistant bacteria, especially Klebsiella pneumoniae and Acinetobacter baumannii. At present, there are concerns regarding the testing and interpretation of tigecycline susceptibility to bugs such as K. pneumoniae and A. baumannii, which limit clinicians in appropriate usage. Use of appropriate method for testing such as broth microdilution is essential. In addition, tigecycline susceptibility testing is a challenge due to inconsistent results from various antimicrobial susceptibility testing automated platforms. There is a great need to define a suitable methodology along with interpretive criteria, especially for K. pneumoniae and A. baumannii. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the Food and Drug Administration (FDA) breakpoints show wide variation and are defined for different set of organisms. Non-species-related pharmacokinetic/pharmacodynamic (PK/PD) breakpoints defined by the EUCAST can be used for organisms such as K. pneumoniae and A. baumannii.

Susceptibility profile, resistance mechanisms & efficacy ratios of fosfomycin, nitrofurantoin & colistin for carbapenem-resistant Enterobacteriaceae causing urinary tract infections.

Background & objectives: The escalation in carbapenem resistance among Enterobacteriaceae has resulted in a lack of effective therapeutic alternatives. Older antimicrobials, fosfomycin, nitrofurantoin and colistin for urinary tract infections (UTIs) caused by carbapenem-resistant Enterobacteriaceae (CRE) may be effective treatment options. The objectives of this study were to evaluate the utility of fosfomycin, nitrofurantoin and colistin in treating UTI caused by CRE and molecular characterization of the plasmid-mediated carbapenem resistance mechanisms. Methods: Consecutive, non-duplicate isolates of CR Escherichia coli and Klebsiella spp. from urine cultures were included (n=150). Minimum inhibitory concentrations (MIC) were determined by E-test (fosfomycin and nitrofurantoin) and broth microdilution (colistin). Efficacy ratios were derived by dividing susceptibility breakpoints by observed MIC values of the drugs for the isolates. Isolates were screened for genes coding for carbapenemases using multiplex PCR. Fosfomycin, nitrofurantoin and colistin-resistant isolates were screened for plasmid-borne resistance genes fos A3, oqx AB and mcr-1, respectively using PCR. Results: Among E. coli, 98.9, 56 and 95 per cent isolates were susceptible to fosfomycin, nitrofurantoin and colistin, respectively, while 94 and 85 per cent of Klebsiella spp. were susceptible to fosfomycin and colistin, respectively. The efficacy ratios indicated fosfomycin as the drug of choice for UTI caused by CR E. coli and Klebsiella spp., followed by colistin. The blaNDM gene was most common, followed by blaOXA48-like. Plasmid-borne genes encoding resistance to fosfomycin, nitrofurantoin and colistin were absent. Interpretation & conclusions: With increasing resistance against the current treatment options, older drugs may emerge as effective options. Molecular screening of resistant isolates is essential to prevent the spread of plasmid-borne resistance against these drugs.

Determination of Biofilm-Forming Capacity of Otopathogens Isolated from Discharging Ears in Children with Chronic Otitis Media.

Chronic otitis media is a common disease of the developing world with persistent ear discharge, leading to major complications. This study describes the microorganisms isolated from the middle ear and nasopharynx of children with chronically discharging ears. Middle ear and nasopharyngeal swabs from 89 children were studied, and the microorganisms isolated were assessed for biofilm-forming ability. Methicillin-susceptible Staphylococcus aureus was common in the nasopharynx, while the middle ear showed predominantly pseudomonas and Methicillin-resistant S. aureus. Pseudomonas aeruginosa showed strong biofilm formation, whereas Escherichia coli, Proteus sp. and Providentia sp. were weak biofilm producers. S. aureus isolates were negative for biofilm formation.

A case of septicaemic melioidosis: Utility of therapeutic drug monitoring and high-dose meropenem in successful management.

Melioidosis is an emerging infectious disease of major public health importance. We describe a patient who presented with septicaemic melioidosis with multi-organ dysfunction. He had only marginal response on standard doses of meropenem. Therapeutic drug monitoring (TDM) revealed suboptimal concentration of meropenem following which drug dose was increased, with which he showed rapid clinical improvement and microbiological clearance. Melioidosis presents with multisystem involvement with disseminated abscess, standard dosing of meropenem may not be sufficient in achieving therapeutic levels and TDM with increased dosing in these critically ill patients will improve outcome.